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Table 2 Summary of values from which the power of the study are estimated

From: Genetic test to stop smoking (GeTSS) trial protocol: randomised controlled trial of a genetic test (Respiragene) and Auckland formula to assess lung cancer risk

 

Control group expected quit rate as %ge

Respiragenegroup expected quit rate as %ge

χ2calculated from four-some table

P value based on χ2

Power calculations*

8 weeks

Sample size 30/30*

70%

94%

5.9

<0.05

79.3%

Sample size 60/60*

11.7

<0.01

96.9%

6 months

Sample size 30/30**

35%

52%

1.7

NS

36.5%

Sample size 60/60**

6.2

<0.05

87.1%

  1. *Telephone (alone) quit rate (see Table 1) assumed to be 20%.
  2. **Telephone (alone) quit rate (see Table 1) assumed to be 10-15%.